Electron beam sterilization apparatus

ABSTRACT

Improved electron beam sterilization apparatus and shielding techniques for use in are provided. A controller modulates an electron beam when sterilizing an interior to an object to ensure that adequate dose is received. Sterilization carousels are configured with input/discharge feeds to reduce the possibility of humans being exposed to dangerous levels of radiation. The system reduces the amount of shielding required to thereby lower cost of installation.

RELATED APPLICATIONS

The present invention is a Continuation in Part of U.S. patentapplication Ser. No. 12/770,083, filed Apr. 29, 2010, by Bufano et alfor EBEAM STERILIZATION APPARATUS, which claims priority to U.S.Provisional Application No. 61/227,566, filed on Jul. 22, 2009 by Bufanoet al., for EBEAM STERILIZATION APPARATUS, and also claims priority toU.S. Provisional Application No. 61/288,569, filed on Dec. 21, 2009 byThomson et al., for SHIELDING FOR ELECTRON BEAM STERILIZATION, and alsoclaims priority to U.S. Provisional Application No. 61/174,061, filed onApr. 30, 2009 by Walther et al., for EBEAM STERILIZATION OF DEEP HOLETARGETS, the contents of each of these applications is herebyincorporated by reference.

FIELD OF THE INVENTION

This invention relates to electron beam (ebeam) sterilization, and morespecifically to an electron beam sterilization of and electron beamsterilization system designs for aseptic filling applications forbottles and other packaging containers used for packaging food,beverages, pharmaceutical, ophthalmic and other products.

BACKGROUND OF THE INVENTION

It is well known in the art that many packaged products including food,beverage, pharmaceutical, ophthalmic, and medical products are producedusing microbiologically clean (i.e. sterile) packaging conditions inorder to improve safety, shelf life, and quality of the end product.Processes using sterile packaging conditions may be referred to asaseptic packaging, extended shelf life (ESL) packaging, shelf stablepackaging and/or ultra clean packaging. The level of sterility (i.e.degree to which packaging surfaces and processing conditions are free ofmicrobes) depends on many conditions including the product beingpackaged (e.g., pH level of product), varying state and countryregulations, and the intended shelf life of the packaged product.Sterile packaging conditions are achieved by sterilizing or disinfectingpackaging material, sterilizing or pasteurizing the product to bepackaged, filling the package with the product in a sterile environment,and sealing the package in the sterile environment.

Packaging sterilization is typically accomplished with heat or chemicalbased sterilants. These traditional methods of sterilization have noteddisadvantages including, but not limited to:

-   -   High heat requires more thermally resistant packaging designs        which are typically heavier and more expensive, and less        environmentally sustainable    -   High heat requires higher energy consumption and costs    -   Chemicals are expensive and difficult and dangerous to maintain        onsite    -   Heat and chemical based sterilization systems are complicated        and present difficulties in terms of maintaining sterility    -   Chemical based sterilants may need to be removed with water,        creating added expense and environmental pollution    -   Chemical based sterilants may leave residual traces on packaging        material that could potentially contaminate packaged product.

It is well known in the art that electron beams are utilized forsterilization (disinfection/decontamination) of packaging materials,such as flexible packaging plastic films, caps and closures, plastic andglass cups and jars, preformed pouches with or without spouts, preformedplastic bags with or without spouts, bottles, cans, and/or paper boardcontainers. A number of noted disadvantages arise in the use of electronbeams for sterilization of packaging materials. A first noteddisadvantage in such sterilization is that maintaining adequate(sufficient/uniform) electron beam dose may be difficult in modernproduction environments. Illustratively, when sterilizing the interiorof bottles or other packaging materials, an appropriate dose is requiredto ensure that sterilization occurs. Should the dose received exceed anupper threshold, undesirable effects may occur to the packagingmaterials. Similarly, should the dose fail to exceed a minimumthreshold, incomplete sterilization may occur, thereby resulting incontamination of the packaged product. In an exemplary bottlesterilization environment, if a bottle is moved relative to an electronbeam emitter, portions of the interior the bottle may receive excessivedosage whereas other regions may receive doses outside of an acceptablerange. It is thus desirous to ensure that the dose along the entireinterior region falls within an acceptable range to ensure propersterilization with no side affects (i.e., maintaining dose uniformitywithin an acceptable range). Beyond the bottle illustration, thechallenge of maintaining dose uniformity exists for all threedimensional products.

A further noted disadvantage of the use of electron beams forsterilization is that they generate x-ray radiation as a byproduct.Electron beams and these byproduct x-rays, as forms of ionizingradiation, are hazardous (i.e., carcinogenous), can cause tissue damageand as such there exist government regulations and manufacturing bestpractices that limit the amount of radiation workers can be exposed toduring a typical operation and/or maintenance. As such, it is necessaryto utilize appropriate shielding for electron beam processes andassociated apparatus in a production environment to prevent undesiredhuman exposure to ionizing radiation. Shielding is typically achieved byutilizing some thickness of a material that is incapable of beingpenetrated by electron beam or x-ray radiation, e.g., lead, andutilizing an appropriate material handling scheme that enables continualor intermittent transport of material into, through, and out of theelectron beam process area while keeping ionizing radiation entering theoperating area below a threshold. The shielding material used may becoated with one or more additional layers of differing materials toimprove resilience, and/or maintain sanitary operating conditions,and/or to protect the electron beam blocking material. The materialhandling system may incorporate a range of configurations and structuresincluding, labyrinth paths, change in elevation, shutter doors, bafflesto improve the shielding efficiency and reduce the overall size andexpense of shielding systems.

Certain prior art shielding systems utilize fully shielded rooms inwhich the sterilization process occurs. In such environments, humanoperators do not enter the production space during sterilizationoperations. A noted disadvantage of creating shielded rooms is that thesize of a production room may be significant, thereby requiringsubstantial costs in procuring materials to create the shielded room.

Certain techniques have been developed to reduce the size and materialrequired to produce effective shielding for production environments thatutilize web based materials. For example, U.S. Pat. No. 4,252,413,entitled METHOD OF AND APPARATUS FOR SHIELDING INERT-ZONE ELECTRONIRRADIATION OF MOVING WEB MATERIALS, the contents of which are herebyincorporated by reference, describes one technique for shielding in aweb based material environment. However, a noted disadvantage of suchsystems is that they are not suitable for use in non-web basedenvironments, e.g. for sterilization of liquid packaging containers,such as bottles or cups.

Exemplary techniques for sterilization are taught in U.S. Pat. No.6,407,492, entitled ELECTRON BEAM ACCELERATOR, U.S. Pat. No. 6,833,551,entitled ELECTRON BEAM IRRADIATION APPARATUS and U.S. Pat. No.7,759,661, entitled ELECTRON BEAM EMITTER, the contents of such patentsand patent application are hereby incorporated by reference. However,these techniques include a number of noted disadvantages. For example,they fail to provide support to correct the intermittent interruption ofelectron beams by, e.g., arcs, nor do they provide the ability tocontinue operations when a single emitter fails. Further, they fail tocontrol dose uniformity for irregularly shaped geometries.

SUMMARY OF THE INVENTION

The present invention overcomes the disadvantages of the prior art byproviding a system and method for open mouth container sterilizationthat ensures that the electron beam dose delivered falls within anappropriate range on the entirety of the interior of the object beingsterilized. One or more sensors may monitor the electron beam dose andare operatively interconnected with a controller. A control systemmodulates the electron beam to ensure that appropriate dose isdelivered. The control system may modify a speed at which the objectbeing sterilized is raised/lowered around a nozzle of an electron beamemitter to ensure that an appropriate dose is received. The controlsystem monitors electron beam performance and coordinates systemrecovery actions in the event of electron beam malfunction. Further, oneor more additional electron beam emitters may be configured to sterilizethe exterior of the object as its interior is being sterilized with thecontrol system similarly coordinating operation. Alternatively, a singleelectron beam maybe used to sterilize the interior of the object andsufficient exterior surfaces to maintain sterile filling conditions.Once sterilized, an electron beam may also be used to sufficientlymaintain sterility of the interior and exterior surfaces until theobject is fully transferred to the sterile zone of the filling system.

The present invention further provides a system and method for improvedshielding for electron beam sterilization. A sterilization carouselcomprising a plurality of electron beam emitters is operativelyinterconnected with one or more power supplies. Each electron beamemitter is configured to provide a sufficient dose to a bottle as anozzle of the electron beam emitter is inserted into the bottle. Thesterilization carousel is appropriately shielded and is operativelyconnected with an input/discharge feed apparatus that is also shieldedin a manner to require any x-rays created in the electron beam processzone to intercept the shielding at least three times before they reachan unshielded portion of the apparatus. The input/discharge feedmechanism may comprise a linear feed, an enclosed labyrinth feed, a duallabyrinth feed, and/or the carousels utilizing baffles in accordancewith various embodiments of the present invention.

The present invention further provides a system and method forsterilization of deep hole targets that utilizes variations in gasmixtures to improve electron beam performance. Illustratively, a lightgas is utilized that completely fills an interior of an object to createa uniform gaseous environment to improve electron beam performance ofdeep hole targets.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages of the invention may be better understood by referring tothe following description in conjunction with the accompanying drawingsin which like reference numerals indicate identical or functionallysimilar elements:

FIG. 1A is a diagrammatic view of an exemplary ebeam sterilizationapparatus in accordance with an illustrative embodiment of the presentinvention;

FIG. 1B is an alternative diagrammatic view of an exemplary electronbeam sterilization apparatus in accordance with an illustrativeembodiment of the present invention;

FIG. 2A is a side elevational view on a larger scale showing a portionof the exemplary electron beam sterilization apparatus in greater detailin accordance with an illustrative embodiment of the present invention;

FIG. 2B is a side elevational view showing a portion of the exemplaryelectron beam sterilization apparatus sterilizing exterior surfaces of abottle in accordance with an illustrative embodiment of the presentinvention;

FIG. 2C is a side elevational view showing a portion of the exemplaryelectron beam sterilization apparatus sterilizing an interior of achamber using a wider beam in accordance with an illustrative embodimentof the present invention;

FIG. 3 is a similar view showing another part of the exemplary electronbeam sterilization apparatus in detail in accordance with anillustrative embodiment of the present invention;

FIG. 4 is a graphical diagram comparing the sterilizing electron beamdose distribution for a typical bottle using a fixed electron beamemitter output and constant speed relative to the emitter with anidealized distribution for that bottle in accordance with anillustrative embodiment of the present invention;

FIG. 5 is a graph showing electron beam sensor output as a function ofemitter beam current in accordance with an illustrative embodiment ofthe present invention;

FIG. 6 is a block diagram showing the supervisory controller of theexemplary electron beam sterilization apparatus and relevant inputs toand outputs from that controller in accordance with an illustrativeembodiment of the present invention;

FIG. 7 is a top cutaway view of an exemplary enclosed electron beamlabyrinth sterilization carousel environment in accordance with anillustrative embodiment of the present invention;

FIG. 8 is a schematic diagram of an exemplary enclosed electron beamlabyrinth sterilization environment in accordance with an illustrativeembodiment of the present invention;

FIG. 9 is a top view of an exemplary enclosed electron beam labyrinthsterilization environment with linear input and discharge feeds inaccordance with an illustrative embodiment of the present invention;

FIG. 10 is a schematic diagram of an exemplary enclosed electron beamlabyrinth sterilization environment with linear input and dischargefeeds in accordance with an illustrative embodiment of the presentinvention;

FIG. 11 is a partial cutaway view of an exemplary enclosed electron beamlabyrinth sterilization environment with linear input and dischargefeeds showing a removable shield for electron beam power supplies andemitters in accordance with an illustrative embodiment of the presentinvention;

FIG. 12 is a top view of an exemplary enclosed electron beamsterilization labyrinth environment utilizing carousel-based baffles inaccordance with an illustrative embodiment of the present invention;

FIG. 13 is a cutaway view of an exemplary enclosed electron beamsterilization environment utilizing baffles in accordance with anillustrative embodiment of the present invention;

FIG. 14 is a schematic diagram of an exemplary enclosed electron beamsterilization environment utilizing baffles in accordance with anillustrative embodiment of the present invention;

FIG. 15 is a cutaway view of an exemplary enclosed electron beamsterilization environment utilizing baffles in accordance with anillustrative embodiment of the present invention;

FIG. 16 is a cutaway view of an exemplary enclosed electron beamsterilization environment utilizing baffles in accordance with anillustrative embodiment of the present invention;

FIG. 17 is a view of an exemplary enclosed electron beam sterilizationenvironment utilizing baffles in accordance with an illustrativeembodiment of the present invention;

FIG. 18 is an exploded view of an exemplary enclosed electron beamsterilization environment showing removable shielding in accordance withan illustrative embodiment of the present invention;

FIG. 19 is an exemplary view of an exemplary enclosed electron beamdouble labyrinth sterilization environment in accordance with anillustrative embodiment of the present invention;

FIG. 20 is a schematic diagram of an exemplary electron beamsterilization apparatus in accordance with an illustrative embodiment ofthe present invention;

FIG. 21 is a schematic diagram of an exemplary electron beamsterilization apparatus showing a shielding cover in accordance with anillustrative embodiment of the present invention.

FIG. 22 is a cutaway view of an exemplary double labyrinth sterilizationsystem in accordance with an illustrative embodiment of the presentinvention;

FIG. 23 is a view illustrating potential x-ray radiation reflectionpaths in accordance with an illustrative embodiment of the presentinvention;

FIG. 24 is a view illustrating potential x-ray radiation reflectionpaths in accordance with an illustrative embodiment of the presentinvention;

FIG. 25 is a view illustrating potential electron beam radiationreflection paths in accordance with an illustrative embodiment of thepresent invention;

FIG. 26 is a view illustrating potential electron beam radiation pathsin accordance with an illustrative embodiment of the present invention;

FIG. 27 is a schematic view of a system for controlling the degree ofscattering of an ebeam projected into a target to achieve increasedebeam penetration in accordance with an illustrative embodiment of thepresent invention; and

FIG. 28 is a schematic view of an alternative system for controlling thedegree of scattering of an ebeam projected into a target to achieveincreased ebeam penetration in accordance with an illustrativeembodiment of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

A. Electron Beam Sterilization of Bottles

FIG. 1A is a diagrammatic view of an exemplary electron beamsterilization apparatus 100A in accordance with an illustrativeembodiment of the present invention. The apparatus 100A includes aninfeed transfer wheel 105, onto which a succession of bottles B isplaced by a loader (not shown) and suspended by grippers securing thebottle from either above or below the neck of the bottle. It should benoted that grippers are described in an exemplary embodiment. Inalternative embodiments, other techniques may be utilized fortransporting bottles. Such alternative techniques may include, e.g.,conveyors, vacuum systems, etc. As such, the description of grippersshould be taken as exemplary only. The bottles are transferred therefromto the grippers 115 of a sterilization carousel 110. As the carousel 110rotates in the direction indicated by arrow 120, the bottles areprocessed and transported in succession to a discharge wheel 125 whichoffloads them into a sterile zone in which downstream processing steps,such as a filling and capping (not shown) take place.

Illustratively, positioned above each bottle gripper 115 is an electronbeam emitter 130. FIG. 2A is a side elevational view of an exemplaryelectron beam emitter 130 environment 200A in accordance with anillustrative embodiment of the present invention. As shown in FIG. 2A,each emitter 130 includes a housing 205 defining a vacuum chamber 210containing an electron beam generator 215. The housing 205 is formedwith an elongated dependent nozzle 220 which is narrow enough to fitinto the finish of the bottles B and which is long enough to extend intothe bottles. An electron beam window 245 is present at the lower end ofeach nozzle. It should be noted that the description of exemplaryelectron beam emitter 130 is illustrative only and that in alternativeembodiments, emitter 130 may contain differing and/or additionalcomponents. As such, the description herein should be viewed asexemplary only.

As the carousel 110 rotates, the bottle grippers 115 thereof are liftedprogressively so that the bottles B are gradually raised around theemitter nozzles 220 to achieve a desired amount of nozzle penetrationinto the bottles. Then, the grippers 115 are progressively lowered toallow the bottles to clear the nozzles 220 before the bottles reach thedischarge wheel 125. As described further below, this penetration of thenozzle into the bottles enables sufficient dosage to be delivered to theinterior of the entire bottle. While it is preferable to move the bottlerelative to the emitter, in alternative embodiments the emitter may moverelative to the bottle.

Each emitter 130 is activated by a power supply 225. The electronsemanating from the nozzle window 210 scatter in air, creating anelectron beam energy plume that extends in 3 dimensions relative tosurface of window. This energy plume sterilizes air and surfaces basedon well known relationships between electron beam dose andmicrobiological reduction (such as published in Cleghorn et. al,“Sterilization of Plastic Containers Using Electron Beam IrradiationDirected through the Opening”, Journal of Applied Microbiology, 2002).Electron scattering due to collisions of electrons with atmosphericmolecules enables electron beam energy to reach surfaces that may bepartially blocked due to the geometry of the surfaces.

As shown in FIG. 1B, in order to sterilize the outside surfaces of thebottles B, one or more stationary electron beam emitters 135 may bepositioned at fixed locations around the carousel 110. Illustratively,the external emitters 135 are arranged such that an external sterilizingdose may be achieved without rotating bottles B about their centralaxis. In alternative embodiments, the bottle grippers 115 may includeprovision for rotating the bottles to expose all sides of the bottlesevenly to the electrons from the outside emitter(s) 135. As such, thedescription of external emitters arranged so that the bottles B do notneed to be rotated about their central axis should be taken as exemplaryonly.

Alternatively, the sterile zone may be defined so as to only require thesterilization of upper portions of the bottle. In this case, theelectron beam emanating from the nozzle may provide sufficientsterilization to upper portions of the bottle before and after thenozzle is inserted into the interior of the bottle. Thus, the number ofexternal emitters may be reduced or avoided altogether. In this case,the relative movement of the nozzle with respect to the bottle wouldprovide sufficient exposure time to effectively sterilize the relevantportions of the exterior of the bottle.

FIG. 2B is a side elevational view showing a portion of the exemplaryelectron beam sterilization apparatus sterilizing exterior surfaces of abottle in accordance with an illustrative embodiment of the presentinvention. Environment 200B shows that an electron beam plume 280 may beutilized to sterilize the exterior of a bottle B. The housing 205 andnozzle 220 enter into the sterile zone 15B and a plume 280 of electronsis generated from the electron beam window 245. The plume 280 is ofsufficient diameter to sterilize the upper surface of bottle B as thenozzle 220 is inserted into the bottle. By controlling the speed atwhich the nozzle 220 is inserted into the bottle, an adequate dose toensure sterilization can be achieved.

FIG. 2C is a side elevational view showing a portion of the exemplaryelectron beam sterilization apparatus sterilizing an interior of achamber using a wider beam in accordance with an illustrative embodimentof the present invention. Environment 200C illustrates that by utilizingsufficiently wide electron beam plumes 280, the interior walls 285 ofsterile zone 15B can be sterilized.

The general operation of a bottle processing carousel such as carousel110 is well known to those skilled in the art. Construction andoperation of exemplary emitters 130, 135 is described, for example, inU.S. Pat. Nos. 5,962,995 and 6,624,229 and U.S. Publication No.2008/0073549 A1, the contents of which are hereby incorporated byreference herein. An alternative approach to bottle sterilization wouldincorporate electron beam emitters position above the mouth of thebottles described in U.S. Pat. No. 6,221,216. Elements of bottlehandling, shielding design and emitter control described herein mayapply to this configuration as well. The overall apparatus may becontrolled by a supervisory controller 605 described further below inreference to FIG. 6.

A clean process zone (or chamber) 150 where the bottles B are sterilizedis illustratively defined by physical partitions 140 and positiveinternal gauge pressure may be provided to prevent ingress ofcontaminants into zone 150. Illustratively, the clean process zone 150may be defined by physical partitions 140 and/or air pressure to providean isolated environment where outside air is prevented from entering.Conventionally, the interior surfaces of chamber 150 as well as thenozzles 220 and other surfaces in the process chamber are cleaned inplace (CIP) with various chemicals and them sterilized in place (SIP)using a chemical sterilant such as vaporized hydrogen peroxide (VHP) orperacetic acid (PAA) or by heat.

It is one important aspect of this invention that instead of usingchemical sterilization or heat to sterilize the external surfaces ofemitter nozzles 220 and the surfaces in the process chamber 150, duringthe SIP cycle, the present apparatus sterilizes such surfaces usingelectron beam radiation.

More particularly, in order to sterilize the surfaces in process chamber150 as part of an SIP cycle, i.e. before the introduction of bottles,emitters 130 may be activated. The electron plumes from the nozzlewindows 210 are free to contact the inside surfaces of housing 140 andother surfaces within chamber 150.

On the other hand, in order to sterilize the emitter nozzles 220themselves, as shown in FIGS. 1B and 3, the emitters 135 provided forexternal bottle sterilization may be activated with bottles absent tosterilize the nozzles as they pass by.

Illustratively, the chamber 150 is configured so that chamber wallsterilization is accomplished using the same number and configuration ofemitters 130, 135 used for container sterilization, although suchoperation may utilize different operating times and/or operating points,e.g., beam current and/or energy. If necessary to allow sterilizationand/or decontamination of the process chamber surfaces, provision may bemade for automatically displacing emitters 130, 135 before and/or duringthe chamber sterilization sequence. Alternatively, one or moreadditional emitters (not shown) may be provided and dedicated to processchamber sterilization.

In any event, such emitter and process chamber sterilization may becarried out simultaneously or sequentially under the control ofcontroller 605, described below in reference to FIG. 6, and be optimizedby proper selection of the emitter beam current and acceleration voltageof the emitters and/or by controlling the environment within chamber 150during SIP, e.g. by providing a light gas or vacuum therein. Usually,the emitter operating parameters set by controller 605 are differentduring the SIP cycle than during the bottle sterilization cycle. Forexample during SIP, some emitters may operate at reduced power to avoiddamage to the windows of other emitters. More generally, the SIPtechniques described herein may be utilized to sterilize other ancillaryequipment, i.e., non-nozzle and/or chamber walls, involved in a bottlingoperation.

During operation, the controlled sterile zone is defined as the boundarybeyond which all machine surfaces and package surfaces interacting withthe product to be packaged satisfy the requirements of sterility. Thissterile zone is maintained with positive air pressure. It is necessaryto ensure that once sterilized, the relevant packaging surfaces remainsufficiently sterile until they move into the controlled sterile zone.In order to ensure the interior of the bottle remains sufficientlysterile until passing into controlled sterile zone, the relativeposition of the electron beam emitter nozzle and bottle may becontrolled so that after interior surfaces are complete, the electronbeam plume may remain on the upper surface and finish of the bottle. Theelectron beam plume supplies sufficient energy such that any microorganism in the air that may otherwise transfer into the bottle interiorthrough the mouth will be sterilized. The bottle will be removed fromthe electron beam plume within the controlled sterile zone, thereforepreventing the possibility of recontamination of the relevant bottlesurfaces before entering the controlled sterile zone. If necessary,exterior sterilization emitters may be positioned to sterilize theexterior surfaces and provide a transfer zone where bottles can betransferred from non-sterile zone to sterile zone without the risk ofrecontamination.

B. Dose Distribution

It is well known to those skilled in the art that the dose delivered toa surface is related to the current, the speed that the surface ismoving and a constant. This relationship may be expressed as:

${Dose} = \frac{K_{({ɛ,V,d})}*{Current}}{Speed}$

where K is a constant that depends on the emitter efficiency (c), theaccelerating voltage (V) and the window to surface distance (d).

When irradiating a three dimensional target such as a bottle B, theusual practice is to move the target at a fixed speed relative to anemitter 130, with the emitter operating at a fixed output energy andcurrent. That is, in the exemplary FIG. 1 apparatus, the bottle grippers115 are moved up and down at a fixed speed. In practice, this may resultin some areas of the three dimensional target, i.e. bottle B, receivingexcessive exposure to electrons which could cause adverse consequences,while other areas receive insufficient exposure to electrons so thatthose other areas are not sterilized adequately.

For example, FIG. 4 shows the emitter dose distribution for a typicalbottle B using a fixed output from an exemplary emitter 130 and aconstant up/down movement of the bottle relative to the emitter inaccordance with an illustrative embodiment of the present invention. Inthis example, a dose over 50 kGy is considered an excessive dose while adose under 25 kGy is considered an insufficient dose. It should be notedthat in alternative embodiments, the 25 and 50 kGy doses may vary and/orbe substituted with differing values depending on the particularenvironment, material, etc. Waveform P₁ in FIG. 4 shows that there is anon-uniform dose distribution due to the three dimensional nature ofbottle B. That is, when the bottle is at positions 1-2 and the window245 of nozzle 220 is in the mouth and narrow neck of the bottle, theelectron beam dose received is too great Likewise for bottle positions9-10 when the window 245 is near the base of the bottle and the relativemotion is being reversed. On the other hand, an insufficient electronbeam dose is delivered to the surfaces at the sides of the bottle atposition 5. Such variations in the applied electron beam dose adverselyaffect the applicability of electron beam sterilization for many suchbottles and other irregular three dimensional targets.

Thus, in accordance with another aspect of this invention, controller605 (FIG. 6) may be programmed to modulate the electron beam dose ratedelivered by an emitter, e.g., emitter 130, 135, to a three dimensionaltarget, e.g. bottle B. Such means may modulate the speed of the targetrelative to the emitter and/or modulate electron beam output from theemitter by altering emitter current and/or beam energy to change thedose rate to the target. The desired dose as a function of relativeposition of nozzle to bottle for a particular target geometry may becharacterized in advance in stored in, e.g., a look up table (see FIG.6). Illustratively, voltage and beam current are held constant in timewhile the relative speed of the container with respect to the stationaryemitter is modulated. In this way, a substantially uniform dosedistribution on the internal surface of the container may be achieved asrepresented by the idealized waveform P₂ in FIG. 4.

Such modulation may also be feedback-controlled by outputs from one ormore sensors that produce a signal(s) related to the dose rate at thetarget and/or the relative positioning of the target.

For example, in case of the bottle shape represented by the waveform P₁in FIG. 4, an excessive dose can be avoided by programming controller605 to use a higher gripper 115 speed at bottle positions 1-2 when eachnozzle 220 is in the mouth and neck of the associated bottle, e.g.higher by, say, a factor of 2-5 times the nominal speed. Also, when theneck is near the base of the bottle at positions 9-10, and the relativemotion is being reversed, the output of the associated emitter may bemodulated by reducing the beam output current and/or energy to create adose rate that is lower by a factor of, e.g., 2-5 times the nominal doserate. On the other hand, at bottle position 5, the gripper 115 may beslowed down and/or the dose rate increased. In any event, the objectiveis to obtain a substantially uniform dose distribution on all theinterior surfaces of the bottle as represented by the idealized waveformP₂ in FIG. 4.

Thus, using the technique described herein, one can prevent bothexcessive and insufficient electron beam doses being applied to a threedimensional target, thereby greatly improving the overall speed andefficiency of such electron beam sterilization processes.

C. Electron Beam Output Measurements

Traditionally, electron beam output may be measured by monitoringfeedback from the emitter power supply and the system controller. Usingthe known relationship of dose, speed, etc., a monitoring system canensure sufficient dose to all surfaces.

In many applications, it may be desirable to measure the electron beamoutput from each emitter explicitly to confirm a reliable and repeatableelectron beam dose at a target such as a bottle B. Traditionally, thishas been done by periodic testing of the dose delivered by each emitter,for example by film dosimetry, and correlation to the power supplied tothe emitter. This is both costly and time consuming and also means thatany changes in beam output efficiency may not be discovered until thenext periodic testing of the electron beam dose.

Thus, another important aspect of this invention is to supplementdosimetry by providing in situ sensors 155 as shown in FIGS. 1A and 3which may monitor the beam outputs of emitters 130, 135 while theapparatus is in operation. The signal from each sensor 155 can then beused for a variety of different purposes. For example, the sensor outputmay be used simply to signal whether the associated emitter is on or offfor maintenance purposes. sensor may also measure electron beam outputwith sufficient accuracy so readings can be compared to baselinereadings taken at startup or installation in order to confirm electronbeam emitter is operating with same efficiency. The dose-speedrelationship may be used to calculate a measure efficiency (K) value tocompare to baseline value in order to confirm emitter is operating atacceptable level of efficiency. If sensor identifies emitter is notoperating properly (i.e. is off or is operating at an efficiency outsideof acceptable levels), it may signal to the supervisory controller thatthe emitter has failed. The sensor may also be used in conjunction witha controller (e.g., controller 240 in FIG. 2) for feedback control toregulate the emitter output based on the sensed signal.

A sensor 155 may be fixed relative to each emitter at shown in FIG. 3or, as seen in FIG. 1A, the two may move relatively so that the sensor155 shown there can sense the output of multiple emitters 130 on thecarousel as they pass by. In either event, this permits the output ofeach emitter to be measured during its operation, thereby ensuring thatthe target surface receives a proper sterilization dose. As noted above,such sensors also enable the monitoring of emitter performance forpreventative maintenance purposes. In accordance with illustrativeembodiments of the present invention, the sensors 155 may collect datato monitor the output of electron beam emitters, to determine theefficiency of emitters, to provide feedback control, etc. Moregenerally, sensors 155 may be utilized to obtain data that may beutilized to provide feedback and/or diagnostic information to controller605 in accordance with alternative embodiments of the present invention.

The sensor 155 may be electrical, thermal, x-ray, visible lightdetection or other type of sensor. Electron beam sensing usingcalorimetry is also feasible. An illustrative suitable electron beamsensor is described in U.S. Pat. No. 6,919,570, the contents of whichare hereby incorporated by reference herein. Alternative sensors mayinclude a negatively biased probe that is directly exposed to theelectron beam in the atmosphere. The electron beam will create secondaryelectrons emitted from the probe and which are accelerated away from theprobe by the negative bias. The measured probe current thus becomes ameasure of the beam output. The sensor 155 may also measure the beamcurrent drawn to a sensor probe from atmospheric plasma when the probehas a positive bias. FIG. 5 is a plot of the sensor output as a functionof ebeam current for those two types of sensors in accordance with anillustrative embodiment of the present invention. As seen there, thesensor output signal is substantially proportional to the electron beamcurrent.

D. Fault Tolerance

In an electron beam sterilization apparatus of this general type, afailure of an emitter 130, 135 or of its power supply 225 will reducethe sterilizing dose of ionizing radiation from that emitter. An emitterfailure often involves a breach of the emitter vacuum chamber 210 (FIG.2), causing a short circuit. This requires that the emitter's powersupply 225 be shut off and that the emitter be disconnected from thesystem or replaced, resulting in potential downtime and lostproductivity. If a single power supply serves several emitters, theproblem is compounded.

Also, an electron beam emitter, like typical high voltage devices,suffers occasional arcing. During an arc, the beam output is disruptedand with it the sterilizing dose of ionizing radiation to the target,e.g. bottle B. Resultantly, some of the bottles B being processed maynot be sterilized adequately.

Thus, it is an additional feature of this invention that provision ismade for monitoring emitter failure and the occasion and duration ofemitter arcing to determine whether or not a proper sterilizationelectron beam dose has been applied by that emitter to a particularbottle.

For this, the supervisory controller 605 (FIG. 6) may keep track of theposition of all the bottles entering the overall conveyor system and,using the data from the LUT, may calculate the proper beam set point foreach emitter.

The desired dose range can be loaded into the controller 605 at thebeginning of each run and the value of the current measured in real timeusing known means. If the current value falls outside the allowableband, the controller may initiate the actions described below.

In response to an emitter failure, the controller 605 may performrecovery operations depending on the type of failure detected. If ahard, i.e., non-arc, failure is detected that will requirereplacement/off-line repair of an emitter, the controller 605 may sendinstructions to the loader in FIG. 1A to not load bottles to the stationof the infeed wheel 105, that corresponds to the carousel 110 positioncontaining a defective emitter 130. For example, in a thirty-heademitter carousel 110, if one emitter 130 fails, the controller 605 mayleave one open position for every twenty nine bottles introduced intothe conveyance line by the loader. This ensures that the failed emitteris “skipped” thereby ensuring that bottles are not improperlysterilized.

Should the controller determine that particular bottles have not beenproperly sterilized due to an electron beam emitter failure, thecontroller 605 will track the bottles B served by the defective emitter130 and eject them from the line after they leave the carousel 110, say,by activating a stationary linear actuator (not shown) positioned underthe transfer wheel 125 in FIG. 1 causing the actuator to “kick” thepotentially improperly sterilized bottles B from the line.Alternatively, the actuator may mark the improperly sterilized bottlesas “defective” and hence subject to rejection down the line.Alternatively, the gripper may “drop” the affected bottle while on thesterilization carousel to a rejection system (not shown) below.

Should an arc event be detected, i.e., the defective emitter isproducing at least some beam output, the controller 605 may analyzewhether the bottle will accumulate sufficient dose on all surfaces inorder to be classified as sterile. It may be preferable to set thetarget minimum dose to some level above the required minimum dose inorder to compensate for occasional arc events. If the controllerdetermined that insufficient dose is delivered due to an arc event, itmay modify the power to that emitter and/or the vertical stroke of theassociated gripper 110 so that the bottle B does receive the properelectron beam does, e.g., if an arc occurs, the rest of stroke cycle maybe slowed down to compensate. Alternatively, the controller 605 mayinitiate proper control operations to the carousel and defective emitterso that the associated bottle receives the reduced electron beam dosesat one or more successive steps or increments of the carousel until thereduced doses total the correct amount. For example, the controller 605may slow the line speed down to allow an emitter operating at reducedpower additional time to complete sterilization of a bottles.

In the case of the external emitter(s) 135, extra emitters may beutilized to provide such dose redundancy. Thus, if one emitter, say,emitter 130, fails, the controller 240 may switch out the emitter andactivate its mate. Preferably, during normal operation of the apparatus,the two emitters (primary and secondary) are both operated at halfpower. Then, if one emitter fails, the controller 240 may automaticallydouble the power to the other so that the bottles B targeted by thatemitter pair receive a normal electron beam dose.

E. Emitter Identification and Compensation

In a multi-emitter system, such as the FIG. 1 apparatus, shown above inFIGS. 1A, B, it may be desirable to regulate the electron beam levels,energy or current i, to compensate for differences in efficiency andprovide consistent dose, across all the emitters. For this, a novelapparatus in accordance with an illustrative embodiment may include anemitter control system which can automatically adjust the emitter setpoints when the emitters are replaced, all with little or no operatorintervention and with limited down time.

Accordingly, it is a further aspect of this invention to provide anautomatic emitter identification and compensation arrangement which canimprove the up-time of a multi-emitter system such as the exemplaryapparatus in FIGS. 1A, B. For this, an ID tag 230 such as a bar code,RFID tag, printed label, marking or the like may be provided on eachemitter 130, 135 as shown in FIG. 2. Preferably, the ID tag carriesreadable data reflecting certain emitter characteristics includingemitter efficiency. Also, as shown in FIG. 2 the apparatus may includean appropriate ID tag reader 235 capable of reading any data on theparticular ID tag 230 as the associated emitter moves by, or isopposite, the reader.

Preferably, each emitter 130, 135 has a dedicated emitter controller 240associated with that emitter's power supply 225 as shown in FIG. 2. Allof the emitter controllers 240 are, in turn, be controlled by thesupervisor controller 605 (FIG. 6) which is responsible for the overalloperation of the apparatus, including that of the emitters.

Generally, there are two types of reading systems, namely “centralized”and “distributed”. In a centralized system, the supervisory controller605 receives data from each ID tag reader 235 and provides each emitterwith a modified set point based on the stated efficiency of eachemitter.

On the other hand, in a distributed system, each emitter controller 240should include a reader 235 capable of reading data from the associatedemitter label. Then each emitter controller 240 can modify the powersupply 225 for that emitter based on the actual emitter efficiency, thenominal set point being provided by the supervisory controller 605.Alternatively, a serial numbering device may be attached to each emitterand connected by a dedicated cable to that emitter's controller 240. Asanother option, communication to a serial memory may be “piggy-backed”on an existing electrical connection, for example, via modulation of acarrier frequency.

In general, non-contact reading systems such as bar codes, RFID tags,etc. are more appropriate for centralized readers whereas wired systemsare, by definition, more suitable for distributed readers.

In either event, when the emitter characteristics are stored on an IDtag attached to an emitter, the efficiency of the emitter is availabledirectly. On the other hand, when only an emitter ID is on the tag withthe emitter, that ID may be used to retrieve emitter characteristics andefficiency from a database provided by the manufacturer.

Instead of storing efficiency and other data as a bar code on an emitter130, that data may be retained in a separate dedicated data storagedevice such as removable flash memory 250 which is paired with thecorresponding emitter controller 240 as shown in FIG. 2. When the memory250 is plugged into emitter controller 240, that controller controlsthat emitter's power supply 225 to take into account that efficiency ofthe emitter 130.

As indicated above, when irradiating a target with an electron beam in acontinuous flow application, it may be necessary to indicate when aninsufficient electron beam dose has occurred due to arcing in an emittersuch as emitter 130, 135. In the exemplary FIG. 1 apparatus, thesupervisory controller 605 should be able to monitor the output of allof the emitters for arcs to determine which emitters have delivered asufficient dose over any period of time. To do that, each emitter mustbe monitored, either by direct measurement or by continuous networkcommunication with a sufficient resolution or bandwidth to detect evenbrief arc events.

The bandwidth required to monitor multiple emitters increases as thenumber of emitters increases and as the duration of the arcingdecreases. In a multiple emitter system, less bandwidth is required ifeach emitter includes a mechanism to monitor its own arc activity todetermine if that emitter has delivered a sufficient dose to its targetand thereafter report the result to the supervisory controller 605.

Accordingly, it is an additional object of this invention to install thenecessary hardware and software in the supervisory controller 605 to:

-   -   1. control each individual emitter controller 240;    -   2. indicate to each emitter controller 240 when a new target,        i.e. bottle B, has been loaded at the associated emitter        location. This may be a signal from controller 605 that controls        the carousel 110 and coordinates all the emitter controllers        240. The signal may be initiated by an optical, capacitive,        magnetic, inductive, proximity, etc. sensor such as the sensor        255 shown in FIG. 2;    -   3. optionally provide a signal to each emitter controller 240        when the target is to be unloaded from the particular emitter        location;    -   4. monitor the aforesaid signals to establish the time during        which the material is to be exposed;    -   5. count the number of arcs detected by each emitter controller,        or accumulate the total time that radiation is absent due to        arcs for each exposure cycle;    -   6. compare the result of the aforesaid count to a pre-defined or        programmable limit to establish if the bottle material has        received a sufficient dose;    -   7. provide a signal, by a discrete electrical connection or via        a network connected to each emitter controller, to the customer        indicating if the bottle material did or did not receive a        sufficient exposure;    -   8. control the previous signal such that the result of the        exposure cycle is indicated either:        -   i. after the exposure cycle,        -   ii. at the earliest point during the exposure cycle when it            has been established by (6) that a minimum exposure level            has been reached,        -   iii. at the earliest point during the exposure cycle when it            has been established by (6) that a maximum number of arcs            (or duration of radiation loss) has been reached, and    -   9. minimize the communication bandwidth requirement between a        supervisory controller and all emitter controllers by indicating        only the result of the exposure cycle (pass or fail) once per        exposure cycle.

In the counting of arcs in the aforesaid paragraph 5, the arc count maybe stored locally in the emitter controller 240 for each emitter. Thatcontroller may carry out a continuous dose calculation for that emitterand issue a pass or fail signal to the supervisory controller 605, orsend back a dose value to that controller. To detect the arcs, the beamcurrent and/or voltage may be monitored. Alternatively, beam output maybe detected by a sensor such as sensor 155 in FIGS. 1A and 3 may beassociated with each emitter 130, 135. The emitters controllers 240 maykeep track of the dose values locally and control the correspondingpower supplies 225 to raise or lower the electron beam doses from thecorresponding emitters accordingly or send pass/fail signals to thesupervisory controller 605. In either event, the power to thecorresponding emitters may be modified and/or the bottle up/down strokemay be changed to compensate.

Since certain changes may be made in carrying out the above methods andin the constructions set forth, it is intended that all matter containedin the above description or shown in the accompanying drawings shall beinterpreted as illustrative and not in a limiting sense. It should benoted that controller 605 may be implemented as an industrial gradecontroller including, e.g., a PLC, etc. Further, it should be noted thatvarious control processes described herein may be implemented insoftware executing on a processor, hardware, firmware and/or acombination thereof.

F. Shielding Arrangements

In illustrative embodiments of the present invention, a sterilizationcarousel, described above in reference to FIGS. 1A and 1B, is utilizedwith one or more feed mechanisms to enable bottles (or other packaging)to be transported onto and discharged from the sterilization carousel.In accordance with alternative embodiments of the present invention, thesterilization carousel and feed mechanisms are shielded in order tominimize the amount of radiation that escapes from the shielded region.Illustratively, the shielding is configured such that an x-ray mustreflect at least three times before reaching an unshielded region.Exemplary electron x-ray radiation paths are discussed below inreference to FIGS. 23-26. FIGS. 7-22, described further below,illustrate various alternative embodiments for configuring asterilization carousel and input/discharged feed mechanisms inaccordance with various alternative embodiments of the presentinvention. The various embodiments shown and described work to reducethe amount of shielding required, and thereby lower cost, whilemaintaining adequate safety for humans in the vicinity of asterilization carousel during operation.

FIG. 7 is a top cutaway view of an exemplary enclosed electron beamlabyrinth sterilization carousel environment 700 in accordance with anillustrative embodiment of the present invention. An input carousel 710feeds bottles onto the sterilization carousel 705. Input carousel 710may accept bottles from additional carousels (not shown) as they movealong a production line environment. Illustratively, the input carousel710 may be operatively interconnected with a linear feed mechanism toenable the installation of a sterilization carousel 705 and inputcarousel 710 in a linear feeding production environment. As such, itshould be noted that input feed carousel 710 may accept bottles from anytype of the bottle transport mechanism in alternative embodiments of thepresent invention. Sterilized bottles are then discharged onto dischargecarousel 715. The discharged carousel 715 may also be operativelyinterconnected with additional carousels (not shown) configured to movesterilized bottles for later steps in processing, for example fillingwith a liquid. Similarly to that described above in reference tocarousel 710, output carousel 715 may also be operatively interconnectedwith alternative feed mechanisms including, for example, a linear feedmechanism. As such, the illustrative embodiment shown in FIG. 7 shouldbe taken as exemplary only.

Illustratively, region 725 comprises a non-sterile zone. A sterileboundary exists at some point in the sterilization carousel, or directlyafter the carousel, which defines an aseptic zone 720 in which thebottles as well as all machinery surfaces and air are consideredsterile. That is, before the bottles reach the sterile boundary, theyare considered to be non-sterile. Once the bottles have been sterilized,they are discharged onto discharge carousel 715 and are considered to beaseptic and ready for filling with a suitable liquid.

FIG. 8 is a schematic diagram of an exemplary enclosed electron beamlabyrinth sterilization environment 800 in accordance with anillustrative embodiment of the present invention. Illustratively, thelabyrinth environment is the same as that shown above in reference toFIG. 7. A sterilization carousel 705 accepts bottles from the inputcarousel 710 and discharges them to discharge carousel 715. The carouselenvironment 800 is shielded to prevent x-ray radiation from reachingexterior to the shielded environment without requiring a minimum ofthree reflections. Illustratively, shielding is placed along lines 805on the sterilization carousel 705 and the input and discharge carousels710, 715. Illustratively, the shielding comprises lead sandwichedbetween two layers of stainless steel. However, it should be noted thatin alternative embodiments the composition of the shielding may vary. Assuch, the description of a layer of lead between layers of stainlesssteel should be taken as exemplary only. It should be expressly notedthat in alternative embodiments additional and/or differing materialsmay be utilized for the shielding for use in various embodiments of thepresent invention. Furthermore, the relative thicknesses of the layersmay vary depending on the strength of the electron beam emitter is beingutilized. As will be appreciated by one skilled in the art, the moreenergy that an electron beam emitter produces requires thicker shieldingto prevent x-ray radiation from escaping through the shieldingmaterials. In an illustrative embodiment, for electron beam emittersthat utilize 150 kV, a typical shielding would comprise approximately 7millimeters of lead. Typically the lead is clad on either side withstainless steel approximately 30-60 thousands of an inch thick.Alternate shielding mechanisms could be used, e.g., approximately 90 mmof stainless steel with no lead. However, it should be noted that thesevalues are illustrative only and that differing values they be utilizedin accordance with alternative embodiments of the present invention.

FIG. 9 is an exemplary top view of an enclosed electron beam labyrinthsterilization environment 900 with linear input and discharge feeds inaccordance with an illustrative embodiment of the present invention. Anexemplary sterilization carousel 905 is operatively connected with aseries of input carousels 910 that are then connected to a linear inputfeed 905. Similarly, one or more discharge carousels 915 are operativelyconnected to a linear discharge feed 920. In operation, bottles mayenter environment 900 via linear input feed 905 and be accepted into theinput feed carousels 910 before being transferred to the sterilizationcarousel 705. Once sterilized, bottles are fed to discharge carousels915 before being transferred to the linear discharge feed 920.Illustratively, the linear feeds 905-920 may utilize a chain transportmechanism as is well known in the art. In alternative embodimentsadditional and/or differing a linear transport mechanisms may beutilized. Illustratively, the input and discharge carousels 910, 915 areof a smaller diameter than the sterilization carousel 705. However, inalternative embodiments the various sizes may differ. As such, it shouldbe noted that the representation of the input and discharge carouselshaving a smaller size than the sterilization carousel should be taken asan exemplary only. The environment 900 illustrated in FIG. 9 may beutilized to implement a sterilization carousel in productionenvironments that utilize linear feed mechanisms. By utilizing aplurality of input and discharge carousels 910, 915, the region to beshielded may be reduced, thereby saving expenses in material forshielding.

FIG. 10 is a schematic diagram of an exemplary enclosed electron beamlabyrinth sterilization environment 1000 utilizing linear input anddischarge feeds in accordance with an illustrative embodiment of thepresent invention. Environment 1000 represents a similar environment tothat shown above in reference to FIG. 9. A sterilization carousel 705excepts bottles from a plurality of input carousels 910 and dischargessterilized bottles onto discharged carousels 915. A linear input feed905 of bottles feed to input carousels 910. Similarly, a lineardischarge feed 920 accepts bottles from discharge carousels 915. Theshaded region represents the area of the sterilization carousel andinput/discharge carousels that would be shielded in accordance with anillustrative embodiment of the present invention. By reducing the sizeof the region to be shielded, there is a concomitant savings in the costof shielding. Furthermore, the exemplary environments 900, 1000illustrate techniques for enabling a sterilization carousel to beutilized with linear feed production environments. That is, asterilization carousel may be easily integrated into a pre-existingsystem or environment that utilizes linear feed mechanisms.

FIG. 11 is a partial cutaway view of an exemplary enclosed electron beamlabyrinth sterilization environment 1100 having linear input anddischarge feeds illustrating a removable shield in accordance with anillustrative embodiment of the present invention. Illustratively, theelectron beam power supplies and emitters are covered by shielding 1105.In an illustrative embodiment of the present invention, shielding 1105may be removable to enable access to the electron beam power suppliesand/or emitters for repair and/or maintenance. In alternativeembodiments of the present invention, a maintenance access hatch (notshown) may be integrated into the shielding 1105. The hatch, which maybe any radiation tight hatch, may be opened to enable access to one ormore of the power supplies and/or emitters.

FIG. 12 is a top view of an exemplary enclosed electron beamsterilization labyrinth environment 1200 that utilizes a carousel-basedbaffles in accordance with an illustrative embodiment of the presentinvention. A sterilization carousel 705 accepts bottles from a inputcarousel 1210 and discharges bottles onto a discharge carousels 1215.Input carousel 1210 may accept bottles from additional carousels 1205.Similarly, discharge carousel 1215 made offload bottles to additionaloutput carousels 1220. Illustratively, the input and output carousels1210, 1215 include a plurality of baffles 1225 that extend radially froma center of the carousel. The baffles 1225 provide additional shieldingbetween bottles to further reduce the amount of radiation that may bereleased in environment 1200. Illustratively, the baffles 1225 do notnecessarily need to extend all the way to an outer wall of carousels1210, 1215. As long as the baffles 1225, which are illustrativelycomprised of appropriately shielded materials, are of a sufficient sizeto reduce the possibility of x-rays escaping from sterilization chamberto unshielded areas without requiring three reflections.

FIG. 13 is a cutaway view of an exemplary enclosed electron beamsterilization environment 1300 utilizing baffles in accordance with anillustrative embodiment of the present invention. As can be seen inexemplary environment 1300, input and output carousels 1210, 1215include baffles 1225 that extend above and below the height of bottlesbeing sterilized. Additionally, carousels 1210, 1215 include appropriategripping mechanisms between each baffle to maintain bottle placement andpositioning. It should be noted that in alternative embodimentsadditional and/or differing transport mechanisms may be utilized. Assuch, the illustration of gripping mechanisms being utilized forconveying bottles along carousels should be taken as exemplary only.

FIG. 14 is a schematic diagram of an exemplary enclosed electron beamsterilization environment 1400 utilizing baffles in accordance with anillustrative embodiment of the present invention. In this view 1400,baffles 1225 extend further radially than that shown in exemplaryenvironment 1200 above. In such an environment 1400, shielding 1405 maybe placed along the exterior of the sterilization carousel and the inputand output carousels 1210, 1215. As will be appreciated by one skilledin the art, by utilizing baffles along the interior of carousels, thenumber of potential reflection angles is reduced, thereby substantiallyreducing the shielding required to ensure that the x-ray radiation thatescapes from the shielded environment has reflected at least threetimes.

FIG. 15 is a cutaway view of an exemplary enclosed electron beamsterilization environment 1500 utilizing baffles in accordance with anillustrative embodiment of the present invention. Sterilization carousel705 is operatively interconnected with a first and second inputcarousels 1505, 1510 as well as first and second discharge carousels1515, 1520. It should be noted that the description of the two inputand/or discharge carousels to be taken as exemplary only. It isexpressly contemplated that in alternative embodiments of the presentinvention, a varying number of input/output carousels may be utilized.Carousels 1505, 1510, 1515 and 1520 illustratively each include aplurality of baffles 1225. In alternative embodiments of the presentinvention, the baffles 1225 may be configured so that they overlap withbaffles 1225 from an adjacent carousel. That is, baffles 1225 oncarousels 1505, 1510 overlap as the carousels rotate. Similarly, baffles1225 on carousels 1515, 1520 may overlap. This may be utilized toprovide additional shielding and further reduce amounts of x-rayradiation emitted.

FIG. 16 is a cutaway view of an exemplary enclosed electron beamsterilization environment 1600 carousel utilizing baffles in accordancewith an illustrative embodiment of the present invention. As can be seenfrom environment 1600, baffles 1225 extend above the level of bottlesand provide obstructions for potential electron beam radiation. As notedabove, in alternative embodiments of the present invention, baffles 1225may be aligned so that they overlap during operation. That is, baffles1225 on carousels 1505, 1510 may overlap, thereby providing additionalsecurity against spurious x-ray radiation. However, it should be notedthat overlapping of baffles is not required. Baffle size may be selectedby a manufacturer to ensure that x-ray radiation paths are limited inaccordance with the principles of the present invention.

FIG. 17 is a perspective view of an exemplary enclosed electron beamsterilization environment 1700 utilizing baffles in accordance with anillustrative embodiment of the present invention. As can be seen in thisperspective view of environment 1700, shielding 1705 to be placed overelectron beam the emitters and power supplies. As discussed above inrelation to FIG. 11, shielding 1705 may be removable. The shielding 1705may be removed to enable maintenance and/or repair of electron beam thementors and/or power supplies and associated apparatus. Furthermore, amaintenance hatch (not shown) may be installed on shielding 1705 toenable easy access for repair without requiring removal of the entireshielding mechanism 1705.

FIG. 18 is exploded view of an exemplary enclosed electron beamsterilization environment 1800 showing removable shielding in accordancewith an illustrative embodiment of the present invention. Environment1800 illustrates shielding 1705 being removed. As noted above, shielding1705 may be removed for maintenance and/or repair operations.

FIG. 19 is a top view of an exemplary enclosed electron beam doublelabyrinth sterilization environment 1900 in accordance with anillustrative embodiment of the present invention. Environment 1900includes a sterilization carousel 705 that is surrounded by an enclosedinput labyrinth 1910 that is surrounded by an enclosed input labyrinth1910. The input labyrinth 1910 receives bottles from a set of inputcarousels 1905. An interior labyrinth carousel 1915 moves bottles fromthe exterior input labyrinth 1910 into the interior of the sterilizationcarousel 705. Output carousels 1925 takes bottles from the sterilizationcarousel 705 and moves them to the exterior discharge labyrinth 1930.Bottles are then removed onto output carousels 1935.

FIG. 20 is a top view of an exemplary double labyrinth sterilizationcarousel environment 2000 in accordance with an illustrative embodimentof the present invention. Environment 2000 corresponds to environmentshown in FIG. 19. As will be appreciated by one skilled in the art, bymaintaining the sterilization carousel 705 within an interior labyrinth,the chance of spurious emission of radiation is further reduced. Thedouble labyrinth design may be utilized as a technique to saveproduction of floor space in alternative embodiments of the presentinvention.

FIG. 21 is a perspective view of an exemplary double labyrinthsterilization carousel environment 2100 illustrating exterior shieldingin accordance with an illustrative embodiment of the present invention.Environment 2100 includes exterior shielding 2105. As can be appreciatedfrom the perspective view of environment 2100, the shielding covers theelectron beam emitter power supplies and electron beam emitters as wasthe enclosed double labyrinth. It should be noted that in alternativeembodiments of the present invention, shielding 2105 may be removable toenable maintenance and/or repair operations to occur on electron beamthe emitters and/or power supplies and related apparatus. Furthermore,in alternative embodiments, a maintenance hatch may be provided toenable easy access for repair operations.

FIG. 22 is a perspective view of an exemplary double labyrinthsterilization carousel environment 2200 in accordance with anillustrative embodiment of the present invention. Environment 2200illustrates a cutaway view of the shielding 2105 to illustrate theplacement of electron beam emitter power supplies under the shielding.As noted above, in alternative embodiments, the shielding 2105 may beremovable to enable repair and/or maintenance operations to occur.Similar or furthermore, in alternative embodiments a maintenance hatch(not shown) may be placed on shielding 2105 to enable the more routinemaintenance to occur.

G. Electron Beam Radiation Paths in Shielded Enclosures

Typically, to ensure that x-ray radiation is not hazardous for humans,x-rays must be reflected/refracted at least three times to ensure thatthey are attenuated sufficiently. Thus, it is desirable to designshielding systems so that x-rays must be reflected at least three timesto escape from the shielded enclosure. In such designs, any radiationthat escapes from the enclosure is typically at such an attenuated levelthat does not provide health risks for humans. FIGS. 23-26 illustratevarious radiation paths to escape from shielded enclosures in accordancewith various embodiments of the present invention. As shown in thebelow-described figures, each of the shielding arrangements describedherein require a minimum of three x-ray reflections to escape from ashielded region, thereby ensuring that humans are not harmed duringsterilization operations.

Illustratively, for each of the alternative embodiments describedherein, analysis may be performed to identify worst case scenarios toensure that shielding is extended to provide the desired level ofattenuation. By worst case it is generally meant, angles of reflectionthat are most advantageous to x-ray radiation to escape from theshielded region of a sterilization environment.

FIG. 23 is a view illustrating potential x-ray radiation reflectionpaths in accordance with an illustrative embodiment of the presentinvention. Environment 2300 is associated with an exemplary systemutilizing an enclosed carousel for input/discharge, described above inrelation to FIG. 7. As can be seen in environment 2300, exemplary x-rayradiation path 2305 originates within the sterilization carousel 705 andrequires at least reflections to escape from the shielded region. Asnoted above, by analyzing the worst case radiation reflection paths, adetermination can be made on how to minimize shielding in alternativeembodiments of the present invention.

FIG. 24 is a view illustrating potential x-ray radiation reflectionpaths in accordance with an illustrative embodiment of the presentinvention. Environment 2400 is associated with an exemplary systemutilizing dual baffle carousels for input/discharge, described above inrelation to FIG. 15. As can be seen in environment 2400, exemplary x-rayradiation path 2405 originates within the sterilization carousel andrequires at least reflections to escape from the shielded region. Asnoted above, by analyzing the worst case radiation reflection paths, adetermination can be made on how to minimize shielding in alternativeembodiments of the present invention.

FIG. 25 is a diagram illustrating potential x-ray radiation paths inaccordance with an illustrative embodiment of the present invention.Environment 2100 is associated with an exemplary system utilizing asingle baffle fielded carousel for input/discharge, described above inrelation to FIG. 12. As can be seen in environment 2500, exemplary x-rayradiation path 2505 originates within the sterilization carousel andrequires at least reflections to escape from the shielded region. Asnoted above, by analyzing the worst case radiation reflection paths, adetermination can be made on how to minimize shielding in alternativeembodiments of the present invention.

FIG. 26 the view illustrating potential x-ray radiation paths inaccordance with an illustrative embodiment of the present invention.Environment 2600 is associated with an exemplary double labyrinthsystem, described above in relation to FIG. 19. As can be seen inenvironment 2605, exemplary x-ray radiation path 2205 originates withinthe sterilization carousel and requires at least reflections to escapefrom the shielded region. As noted above, by analyzing the worst caseradiation reflection paths, a determination can be made on how tominimize shielding in alternative embodiments of the present invention.

Certain changes may be made in implementing the novel shieldingtechniques set forth, it is intended that all matter contained in theabove description or shown in the accompanying drawings shall beinterpreted as illustrative and not in a limiting sense. Furthermore,while this description has been written in terms of performing in thebottle (ITB) sterilization, the principles of the present technique maybe utilized for sterilization of any non-web-based material including,for example exterior sterilization of bottles or other packagingmaterials. Additionally, while this description is written in terms ofx-ray sterilization, the principles of the present invention may beutilized for other radiation-based sterilization techniques. Similarly,while the description of x-ray requiring at least three reflections tobe attenuated to be safe for humans, the principles of the presentinvention are expressly contemplated to cover varying numbers ofnecessary reflections. As such, the description of the three reflectionscontained herein should be considered an exemplary only.

H. Sterilization of Deep Hole Targets

Electron beam emitters have been used for many years to irradiate andsterilize various targets including the interiors of containers. Thesehollow targets may be characterized by their aspect ratio, that is theratio of their opening size to the length of the target from the openingto the bottom or base. As the aspect ratio increases (that is the lengthincreases relative to the opening), it requires greater and greater beamvoltage to sterilize the interior surfaces along the full length and thebottom. This is due to the scattering of electrons in air as theycollide with air molecules and travel transverse to the length of thecontainer and are absorbed by the target wall. The “scatter length” isthe distance the electron beam will travel through the hollow targetbefore being substantially dispersed due to scattering. As the voltageof the beam increases, the scattering length increases. Since there aremany advantages of low voltage (<150 kV) systems (e.g. less shielding,lower consumption, less packaging material damage, smaller size andexpense), it is desirable to find solutions that overcome the scatteringproblem. This has usually been done in the following ways:

1. For hollow targets with low enough aspect ratios, electron beamemitters are positioned above the container and direct energy throughthe mouth thereof. Sufficient energy is absorbed on all interiorsurfaces of the container including the bottom as discussed in U.S. Pat.No. 3,780,308, the contents of which are hereby incorporated byreference.

2. For hollow targets with high aspect ratios or with a shape thatprevents a beam fixed above the target from reaching all surfaces (e.g.for a bottle), the electron beam emitter is usually formed with a narrownozzle that is dimensioned to project into the target volume through themouth of the target as discussed in U.S. Patent Publication No.2008/0073549A1, the contents of which are hereby incorporated byreference. The emitter is invariably positioned above the target, say,at a station of a rotary carousel so that the nozzle points down towardthe target which may be supported by a vertically movable gripper. Whenit is time to irradiate the target, the gripper is raised up so that thetarget volume surrounds the nozzle. The emitter is then activated sothat a beam of electrons emanating from a window at the distal end ofthe nozzle irradiates the interior surface of the target. The ebeam doseis of sufficient intensity, and lasts for a sufficient time, tosterilize the interior surfaces of the target.

In some cases, the hollow target may have a high enough aspect ratio toprohibit approach 1, but it is not possible or practical to employapproach 2.

In a separate, but related problem, if the target volume has anirregular shape, the lateral dispersion of the electron beam may not besufficient to provide a sterilizing dose of radiation to all side wallsof the target volume.

Some attempts have been made to alleviate the aforesaid problems byproviding electromagnetic beam shaping or directing members outside thetarget which can steer the electron beam in a desired way; see e.g. U.S.Pat. No. 6,139,796, the contents of which are hereby incorporated byreference. However, such members take up critical space in the alreadycrowded environment around the target being sterilized. U.S. PublicationNo. 2008/0073549 A1 teaches extending the range of an electron beam asit is projected into a target volume by introducing a low Z or light gassuch as helium into the volume prior to activating the emitter. Theinteraction of the beam electrons with these lower density gas moleculesresults in a longer ebeam path than would be the case if the targetvolume were filled with air.

In practice, however, it has proven difficult to provide a selected gasenvironment within a target volume which remains stable and consistentthroughout the sterilization cycle. For example, when the selected gasis piped into the target volume, that gas, being lighter than air, tendsto rise up and escape through the open mouth of the container. Thisadverse effect is exacerbated because the target volume e.g., a bottlepreform, is usually supported in a carousel or other such machine whichis subjected to various scripted movements as well as to vibration.

FIG. 27 shows an ebeam emitter 2705 having a narrow nozzle 2705A and apower supply 2710. Whereas such emitters are usually mounted so that thenozzle 2705A faces downward, emitter 2705 is supported by a supportmember 2715 so that its nozzle 2705A faces upward. For example, supportmember 2715 may be a carousel that supports a multiplicity of emitters2705 distributed around the rotary axis of the carousel. Each emitter2705 may be of the type described in U.S. Publication No.2008/0073549A1, the contents of which are hereby incorporated herein byreference. Suffice it to say here that emitter 2705 emits a beam ofelectrons e through a window 2720 at the distal end of nozzle 2705A.

Associated with each emitter 2705 is a gripper 2725 which is adapted tosupport a target to be irradiated. The illustrated target is a bottlepreform P, but the target could just as well be a bottle or otherrelatively deep hollow article.

In any event, the gripper 2725 grips the finish of preform P and isadapted to be rotated by a rotary step motor 2730 under the control of acontroller 2735 so that the preform is either upright or inverted. Themotor and gripper are also movable vertically between an upper positionshown in phantom in FIG. 27 wherein the preform is spaced above nozzle2705A with its mouth P₁ facing upward and a lower position shown insolid lines in that same figure wherein the preform is inverted suchthat its mouth P₁ faces downward and the emitter nozzle 2705A extendsinto the preform. Mechanisms for moving gripper 2725 up and down arewell known in the field of bottle-processing carousels.

Also associated with each emitter 2705 is a gas inlet pipe 2740 whichextends from a source 2745 of a selected light gas such as helium. Thedistal end segment 2740A of pipe 2740 lies close to emitter nozzle 2705Aso that when the gripper 2725 moves the preform P onto the nozzle 2705A,the pipe segment 52740A projects through the mouth P₁ of the preform asshown in 2700. The gas flow from supply 2745 to the preform may beregulated by a valve 2750 under the control of controller 2735.

After the preform P has been moved to its lower position shown in solidlines in environment 2700, controller 2735 may open valve 2750 for aselected time so that the light gas flows into, and completely fills,the interior of preform P. Since the selected gas is lighter than air,it rises to the closed upper end of the preform and displaces all of theair in the preform thus creating a uniform gaseous environment withinthe preform. Then, the controller 2735 may activate the power supply2710 so that a beam of electrons e projects from the distal end of theemitter nozzle 2705A thereby sterilizing the interior surfaces of thepreform. This may occur as the preform is moving vertically relative tothe nozzle as is well known in the art.

After the sterilization step is completed, gripper 2725 may be activatedto move preform P vertically to its upper position shown in phantom inenvironment 2700, after which motor so that the preform is rotated untilits mouth P₁ faces upwards. The light gas inside the preform willthereupon rise up out of the preform to be replaced by ambient air.

Still referring to environment 2700, instead of rotating the preform inorder to remove the selected gas following ebeam exposure, the preformmay remain in its inverted position shown in solid lines and theselected gas purged from the interior of the preform by directing airunder pressure through a tube 2755 that extends to the closed upper endof the preform. Alternatively, a vacuum may be drawn in the preform toachieve the same objective.

Referring now to FIG. 28 which illustrates a second embodiment of theapparatus wherein the emitter 2705 and the target, e.g., a bottlepreform P or bottle B, are operated in an environment that consistsprimarily of the selected gas. The components of environment 2800 thatare more or less the same as those in environment 2700 carry the sameidentifying characters. In the environment 2800, the emitter/targetcombination are contained within a fluid-tight enclosure 2805. Enclosure2805 may be local to each emitter/target pair or it may enclose anentire carousel containing many such pairs. In any event, the volumewithin enclosure 2805 may be filled with a selected gas which is pipedinto that space via a pipe 2740 connected to a gas supply 2745. The flowof gas through pipe 2740 may be regulated by a solenoid valve 2750 underthe control of controller 2735.

If a particular application requires that the ebeam emitted by emitter2705 have a maximum range in the target volume, the housing 2805 may befilled with a light or low Z gas such as helium. On the other hand, ifthe application requires that the ebeam projected into the target volumebe dispersed laterally to a maximum degree, a high mass gas species suchas Xenon may be injected into the housing 2805 so as to fill the targetvolume.

The foregoing description has been directed to particular embodiments ofthis invention. It will be apparent, however, that other variations andmodifications may be made to the described embodiments, with theattainment of some or all of their advantages. For example, whereelectron beam treatment is described for the purposes of sterilization,it may also be for other purposes, e.g., curing of a coating, treating asurface, modifying the properties of the material such as crosslinking,for the purpose of improving chemical, mechanical, and/or thermalresistance properties. ITB sterilization techniques may be utilized withboth rotary fill and linear fill line systems. In alternativeembodiments, the same processes described herein as being utilized priorto filling may be used on containers that have been filled but not yetsealed. For example, in certain applications, it may be preferable tofill the container and then used an electron beam to sterilize the“headspace,” i.e. the portion of the container that has not been filledwith product. It should be noted that while the term sterilization hasbeen used in this description, and where the term sterilization is takento mean something highly specific, it may be replaced with alternativeterms including, but not limited to disinfected, sanitized, microbialreduced, etc.

Additionally, the procedures, processes and/or modules described hereinmay be implemented in hardware, software, embodied as acomputer-readable medium having program instructions, firmware, or acombination thereof. Therefore, it is the object of the appended claimsto cover all such variations and modifications as come within the truespirit and scope of the invention.

1. An apparatus for sterilizing a bottle, the apparatus comprising: amovable electron beam emitter comprising an elongated nozzle having anelectron beam window at a lower end of the elongated nozzle; a pluralityof grippers configured to raise and lower the bottle around theelongated nozzle; one or more stationary electron beam emittersconfigured to sterilize an exterior of the bottle; and a controlleroperatively interconnected with the plurality of grippers and themovable electron beam emitter, the controller configured to modulate anelectron beam dose rate delivered by the movable electron beam emitter.2. The apparatus of claim 1 wherein the controller modulates theelectron beam dose rate delivered by the movable electron beam emitterby varying a speed at which the bottle is raised and lowered by theplurality of grippers.
 3. The apparatus of claim 1 wherein thecontroller modulates the electron beam dose rate delivered by themovable electron beam emitter by varying a current associated with themovable electron beam emitter.
 4. The apparatus of claim 1 wherein theplurality of grippers are configured on a carousal and the movableelectron beam emitter comprises one of a plurality of movable electronbeam emitters arranged to rotate in a synchronous manner with thecarousal.
 5. The apparatus of claim 1 wherein the controller isconfigured to, in response to detecting an arc event associated with themovable electron beam emitter, modify power to the movable electron beamemitter so that the bottle receives an electron beam dose that is withina predefined range.
 6. The apparatus of claim 1 wherein the controlleris configured to, in response to detecting an arc event associated withthe movable electron beam emitter, modify a speed at which the grippersraise and lower the bottle around the movable electron beam emitter sothat the bottle receives an electron beam dose that is within apredefined range.
 7. The apparatus of claim 1 wherein the controller isconfigured to, in response to detecting an arc event associated with themovable electron beam emitter, modify power to the movable electron beamemitter so that the bottle receives an electron beam dose that is withina predefined range.
 8. The apparatus of claim 1 further comprising oneor more sensors operatively interconnected with the controller.
 9. Theapparatus of claim 8 wherein the one or more sensors are configured todetect an output level of the movable electron beam emitter.
 10. Theapparatus of claim 8 wherein the one or more sensors comprise electricalsensors.
 11. The apparatus of claim 8 wherein the one or more sensorscomprise thermal sensors.
 12. The apparatus of claim 1 wherein the oneor more stationary electron beam emitters are oriented so that thebottle does not need to be rotated to ensure that sterilization of theentire exterior of the bottle occurs.
 13. An apparatus for sterilizing aplurality of bottles, the apparatus comprising: a plurality of movableelectron beam emitters, each comprising an elongated nozzle having anelectron beam window at a lower end of the elongated nozzle; a pluralityof grippers configured to raise and lower the plurality of bottlesaround one of the elongated nozzles of the plurality of movable electronbeam emitters; one or more stationary electron beam emitters configuredto sterilize an exterior of the plurality of bottles; and a controlleroperatively interconnected with the plurality of grippers and theplurality of movable electron beam emitters, the controller configuredto modulate an electron beam dose rate delivered by each of theplurality of movable electron beam emitters.
 14. An apparatus forsterilizing a bottle, the apparatus comprising: means for generating anelectron beam; means for raising and lowering the bottle around themeans for generating the electron beam; means for sterilizing anexterior of the bottle; and means for modulating an electron beam doserate delivered by the means for generating the electron beam.